COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1317 Konkoly Observatory Budapest 1977 August 4 HD 20301: AN ECLIPSING, DOUBLE-LINED EARLY G GIANT Recently, Andersen and Nordstrom (1977) found HD 20301 to be a double-lined spectroscopic binary with sharp lines, equal components and small velocity amplitudes. Subsequently the system was found to show eclipses (Olsen 1977). The star is an early G giant, judging from both the photometry and the spectra, and it is a prime candidate for determination of fundamental masses and radii of evolved stars. The system is not an RS CVn binary and does not show any convincing CaII H and K emission on the five 20Angstrom/mm coude spectra available so far (Andersen, private communication). In the group of 24 giant binaries discussed by Lloyd Evans (1977), HD 20301 fits in as a somewhat atypical early member without, or with extremely faint H and K emission. Additional photometry in 1976 and 1977 by Drs. J. Andersen, B. Reipurth and the author has now made it possible to give three tentative ephemerides for the eclipses. The photometry has been obtained with the simultaneous four-channel spectrograph-photometer on the Danish 50 cm reflector on Cerro La Silla, ESO, Chile. The Table gives the individual observations reduced to the standard four-colour and V systems. This table is a continuation of Table 2 in Olsen (1977). The deepest minimum found as yet is 0.28m, 0.25m, 0.21m and 0.19m in u, v, b and y, respectively. We strongly urge observers to observe more eclipses of this extremely interesting system in order to fix the period and improve the ephemeris. The most probable ephemeris is HJD (MinI) = 2443216.14d+37.805d x E (1) with the next eclipses expected at U.T. 1977 Aug. 11.9, Sep. 18.7, Oct. 26.5, Dec. 3.3, 1978 Jan. 10.1, Feb. 16.9 and Mar. 26.7. Primary eclipse may last about 24 hours. An observation within 9 hours of phase 0.5 has not revealed any eclipse. The double period 75.61d cannot be excluded, but the available velocities favour the shorter period. Another possible, but slightly less likely ephemeris is HJD (MinI) = 2443216.67d+50.46d x E (2) with nearly equal primary and secondary eclipses expected at U.T. 1977 Aug. 12.6, Sep. 6.8, Oct. 2,0, Oct. 27.2, Nov. 21.5, Dec. 16.7, 1978 Jan. 10.9, Feb. 5.2, Mar. 2.4 and 27.6. A third possibility, with an excentric orbit and the secondary minimum displaced to phase 0.44 is HJD (MinI) = 2443216.71d+44.18d x E (3) with eclipses expected at U.T. 1977 Aug. 13.3, Sep. 6.9,.Sep. 26.5, Oct. 21.1, Nov. 9.7, Dec. 4.3, Dec. 23.9, 1978 Jan. 17.5, Feb. 6.0, Mar.2.7 and 22.2. The 1980.0 coordinates of HD 20301 are 3h13m53s and -35d37.8'. ERIK HEYN OLSEN Copenhagen University Observatory Brorfelde,Denmark References : Andersen, J. and Nordstrom, B. 1977, Astron.Astrophys.Suppl., in press [BIBCODE 1977A&AS...29..309A ] Lloyd Evans, T. 1977, MNASSA 36, 41 [BIBCODE 1977MNSSA..36...41L ] Olsen, E.H. 1977, Astron.Astrophys.Suppl., in press [BIBCODE 1977A&AS...29..313O ] Table HJD 2440000+ V b-y M1 C1 Observer 3029.80535 6.875 0.466 0.258 0.437 BR 3029.88713 6.878 0.467 0.257 0.434 BR 3030.77558 6.883 0.466 0.253 0.456 BR 3030.88539 6.878 0.474 0.245 0.442 BR 3031.83323 6.879 0.468 0.254 0.443 BR 3031.89801 6.879 0.469 0.258 0.438 BR 3032.75178 6.876 0.466 0.263 0.446 BR 3034.82254 6.880 0.464 0.257 0.441 BR 3034.89308 6.865 0.478 0.260 0.417 BR 3036.78249 6.877 0.469 0.256 0.437 BR 3049.78634 6.883 0.465 0.256 0.452 BR 3050.89130 6.875 0.462 0.265 0.438 BR 3051.75804 6.879 0.469 0.255 0.447 BR 3051.85721 6.880 0.469 0.260 0.438 BR 3052.76996 6.886 0.459 0.276 0.422 BR 3123.75091 6.879 0.461 0.265 0.443 BR 3124.56473 6.874 0.470 0.262 0.437 BR 3125.67673 6.875 0.465 0.268 0.425 BR 3126.77094 6.876 0.465 0.262 0.437 BR 3132.72024 6.889 0.453 0.274 0.452 BR 3133.71853 6.885 0.458 0.272 0.443 BR 3135.70173 6.875 0.458 0.275 0.422 BR 3136.72083 6.879 0.469 0.244 0.464 BR 3142.65766 6.882 0.470 0.245 0.452 BR 3147.69260 6.886 0.474 0.241 0.437 BR 3212.51030 6.874 0.463 0.262 0.422 EHO 3212.52919 6.875 0.467 0.251 0.434 EHO 3212.55007 6.873 0.469 0.249 0.440 EHO 3213.50629 6.868 0.468 0.253 0.432 EHO 3213.52677 6.864 0.465 0.256 0.441 EHO 3213.54912 6.869 0.468 0.248 0.450 EHO 3214.51173 6.876 0.468 0.249 0.446 EHO 3214.53842 6.879 0.462 0.255 0.448 EHO 3215.50912 6.865 0.472 0.248 0.433 EHO 3215.53921 6.883 0.471 0.241 0.458 EHO 3216.50982 7.045 0.489 0.286 0.416 EHO 3216.53556 7.050 0.486 0.287 0.416 EHO 3216.55798 7.055 0.491 0.284 0.418 EHO 3217.51024 6.876 0.471 0.249 0.443 EHO 3217.53876 6.880 0.466 0.257 0.444 EHO 3218.50864 6.881 0.462 0.264 0.431 EHO 3218.53981 6.888 0.464 0.256 0.444 EHO 3219.51239 6.879 0.468 0.252 0.440 EHO 3220.50919 6.877 0.465 0.262 0.432 EHO 3221.51055 6.870 0.468 0.253 0.439 EHO 3222.50940 6.877 0.466 0.257 0.431 EHO 3223.52 6.87: EHO 3224.50 6.87: EHO 3225.50 6.87: EHO 3226.50307 6.879 0.469 0.251 0.422 EHO 3227.49834 6.859 0.461 0.253 0.426 EHO 3228.49854 6.881 0.464 0.258 0.441 EHO 3229.49308 6.881 0.470 0.254 0.439 EHO 3230.49486 6.902 0.467 0.266 0.448 EHO Table (cont. ) HJD 2440000+ V b-y M1 C1 Observer 3231.49516 6.874 0.455 0.276 0.413 EHO 3232.49367 6.866 0.461 0.268 0.423 EHO 3234.49432 6.886 0.465 0.261 0.437 EHO 3235.49148 6.869 0.470 0.250 0.436 EHO 3235.51365 6.882 0.471 0.247 0.467 EHO 3236.49170 6.904 0.479 0.256 0.425 EHO 3237.49130 6.874 0.470 0.256 0.414 EHO 3238.48817 6.874 0.464 0.259 0.445 EHO 3240.488 6.87: EHO 3242.48031 6.895 0.471 0.246 0.452 JA 3245.47404 6.887 0.458 0.264 0.438 JA 3251.47251 6.877 0.461 0.259 0.434 JA 3252.47774 6.917 0.464 0.262 0.417 JA 3254.47612 6.934 0.469 0.247 0.439 JA 3255.47528 6.882 0.463 0.257 0.438 JA 3256.47515 6.856 0.449 0.262 0.400 JA 3256.48065 6.843 0.458 0.258 0.381 JA 3259.47363 6.887 0.449 0.261 0.410 JA 3260.47625 6.907 0.462 0.278 0.395 JA